Transposition insulator for electrical coils



Sept. 18, 1962 F. E. HENDERSON 3,054,845

TRANSPOSITION INSULATOR FOR ELLECTRICAL COILS Filed March 22, 1961 Jun/cub)? (51 11 I 54:6 Hobart .204 1 United States Patent P 3,054,845 TRANSPOSITION INSULATOR FOR ELECTRICAL COILS Floyd E. Henderson, West Allis, Wis., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed Mar. 22, 1961, Ser. No. 97,542 6 Claims. (Cl. 17434) This invention relates to electrical windings such as the type generally found in induction apparatus and more particularly to a transposition insulator for such windings.

In electrical windings of the type generally found in transformers for power distribution it is desirable that the conductors in the windings be transposed or crossed at certain predetermined points. With proper transposition or crossover of adjacent conductors the flux linkage of all the conductors with respect to the induction apparatus core can be equal or approach a perfect balance. With perfect flux linkage there are no circulating currents which would otherwise add to the loss already present from the eddy current copper losses.

In transposing adjacent turns in a winding of an electrical apparatus a problem arises at the point of crossover. The problem is further accentuated when the conductors are of rectangular cross section which is usually the case in windings of power transformers and other large induction apparatus. At the point of crossover, the edges of one conductor rest against the surfaces of the other conductor. Unless proper safeguards are provided, adjacent conductors will tend to rub against each other and damage or weaken their insulation. The rubbing of adjacent conductors at their point of crossover may be caused by vibrations which occur during electrical surges and by movement of the apparatus during shipment.

To prevent vibration of adjacent conductors and the resultant damage of insulation, attempts have been made to securely tie the conductors together in such a manner that movement of them is completely eliminated. While such means for clamping adjacent conductors at their point of crossover are an improvement, elimination of all vibration has not been obtained. Furthermore, vibration is likely to increase as the transformer ages.

Another attempt to solve the damage of insulation caused by the sharp edges of transposed conductors has been to isolate the two conductors from each other at their point of crossover. Such means may consist of inserting kraft paper or other insulating material between the two adjacent transposed conductors, placing wedges at strategic points in the area of crossover and finally binding the paper and Wedges with tape to securely hold all elements. While such means have been found to be highly successful in eliminating damage to the insulation it has also been a somewhat complex solution. To obtain a rigid unit each conductor required wedges on two of its four sides and several layers of kraft paper on each of the other two adjacent sides. Thus, the expense in materials and manpower used to insert the various elements and bind them together has been considerable.

The invention to be described herein overcomes the problems encountered in the prior methods by providing for a unitized transposition insulator which in addition to securely holding a pair of adjacent conductors also isolates them from each other at their point of transposition.

Therefore, it is one object of this invention to provide a new and improved electrical winding.

Another object of this invention is to provide a new and improved means for transposing adjacent conductors in an electrical winding.

Another object of this invention is to provide a new and improved transposition insulator.

Objects and other advantages of this invention will be 3,054,845 Patented Sept. 18, 1962 apparent from the following description when read in connection with the following drawing in which:

' FIG. 1 is an end view in elevation of the transposition insulator of this invention;

FIG. 2 is a top view in elevation of the same;

FIG. 3 is a side view;

FIG. 4 is an isometric view of the transposition insulator as applied to a pair of conductors; and

FIG. 5 is a top view in elevation of a portion of an electrical winding with a transposition insulator of this invention.

As illustrated in FIGS. 14 a transposition insulator 11 of unitized construction is provided which has a pair of transposed conductor receiving grooves 13 and 14. Each of the grooves is formed by a pair of wedge-like projections 16 and 17 extending from opposed top and bottom surfaces '20 and 21. With particular attention to FIG. 3 it can be observed that the bottom surface 21 may be flat. However, in order that the transposition spacer consumes as little space as possible it is preferable that one surface is of a generally convex configuration. Thus, the top surface 20 is substantially curved.

FIG. 1 illustrates how the insulator has a steplike configuration at each end with the ends of surfaces 20 and 21 forming the treads and element 23 forming the riser. Surfaces 20 and 21 provide longitudinal support for conductors 25 and 26. Element 23, which is a thin web between projections 16 and 17, provides lateral support for both conductors. The configuration at the opposite end of the transposition insulator is similar. FIG. 4 illustrates how a pair of contiguous and transposed conductors are secured and isolated from each other by insulator 11. Progressing inwardly from one end of the insulator, conductor 25 is inclined slightly and then, after reaching a height sufiicient to clear the conductor 26, is moved in a diagonal or curved fashion and proceeds downwardly to its original plane. The second conductor 26 stays in the same plane and also makes a diagonal crossover at midsection of the insulator. By providing riser element 23 to come into contact with both of the conductors a very compact insulator is obtained. The insulators height and width may be substantially equal to the combined width of the two conductors.

Assuming that the conductors are of rectangular cross section the transposition insulator provides support for each conductor on at least two surfaces. At the midsection 28 of the insulator each conductor is supported on three surfaces. In such a manner the conductors are interlocked with the insulator and are also isolated from each other, thereby avoiding rubbing of each other.

In installing the insulator and electrical winding, the pair of conductors are crimped at a predetermined point so that they are transposed and are formed to readily fit in the two channels or grooves 13 and 14 of the transposition insulator. Once the two conductors have been crimped by means such as a hand tool designed to form them in a particular configuration, the insulator may be readily inserted onto the conductors. The conductors are then wound about a coil form.

The coil portion in FIG. 5 illustrates a two layer disk coil with the top layer being visible. The transposition insulator is equally suitable for other types of coils. It is to be noted that adjacent turns which are wound in close contact with the transposition insulator cause the two transposed conductors to be firmly locked and seated. The one surface 31 at the area of transposition for each conductor which is not in contact with the insulator will be in contact with adjacent turns 32.

Although the illustrated conductors are snugly held in the transposition insulator, smaller sizes of conductors may also be adequately contained. The conductors will still be isolated from each other. Slight vibrations of under- 3 sized conductors will not be injurious since only smooth surfaces of the insulator are in contact with the conductors.

There are a number of insulating materials which can be readily adaptable for use as transposition insulators. Such materials as epoxy resins, nylon and polypropylene are only a few of the many materials which can be easily molded into the insulators of this invention.

While only one embodiment of this invention has been described it will be obvious to those skilled in the art that modifications can be made within the scope of the appended claims.

What is claimed is:

1. In an electrical winding having a pair of contiguous and transposed conductors, a unitized insulating member having conductor receiving grooves on two opposed surfaces confining said conductors at their curved portions of transposition, said surfaces forming an insulating layer between said conductors at their point of transposition, said insulating member having its width and height substantially equal to the combined width of said two conductors.

2. A unitized insulating member for an electrical winding having a pair of contiguous and transposed conductors, said insulating member having conductor receiving grooves on two opposed surfaces for confining said conductors at their curved portions of transposition, said surfaces forming an insulating layer between said conductors at their point of transposition, each said groove being defined by two projections, each said projection having an extension for serving as a shoulder for said conductor, the width and height of said insulating member being substantially equal to the combined width and height of said conductors.

3. A unitized-insulating member for an electrical winding having a pair of contiguous and transposed rectangular conductors, said insulating member having conductor receiving grooves on two opposed surfaces for confining said conductors at their portions of transposition, said surfaces forming an insulating layer between said conductors at their point of transposition, each said groove being defined by two projections, each said projection having a portion extending away from the point of transposition for serving as a shoulder for one of said conductors, the width and height of said insulating member being substantially equal to the respective width and height of the combined conductors.

4. A unitized insulating member for an electrical windinghaving a pair of contiguous and transposed rectangular conductors, said insulating member having conductor receiving grooves on two opposed surfaces for closely confining said conductors on three sides at their areas of transposition, said surfaces forming an insulating layer between said conductors at their point of transposition, each said groove being defined by two projections, each said projection having a portion extending away from the point of transposition for serving as a shoulder for one surface of each said conductor, the width and height of said insulating member being substantially equal to the respective width and height of the combined conductors.

5. A unitized insulating member for an electrical winding having a pair of contiguous and transposed rectangular conductors, said insulating member having conductor receiving grooves on two opposed surfaces for closely confining said conductors at their curved portions of transposition, said surfaces forming an insulating layer between said conductors at their point of transposition, one of said grooves being substantially convex, each of said grooves being defined by two projections, each said projection having a portion extending away from the point of transposition for serving as a shoulder for one of said conductors, the width and height of said insulating member being substantially equal to the respective width and height of the combined conductors.

6. In an electrical winding having a pair of contiguous and transposed rectangular conductors, a unitized insulating member having conductor receiving grooves on two opposed surfaces closely confining said conductors at their curved portions of transposition, said surfaces forming an insulating layer between said conductors at their point of transposition, said grooves being defined by two dependent segments, each said segment being of stepped configuration and extending from the point of transposition along a straight length of said conductors in engagement with two sides of each said conductor, the middle partition of said stepped configuration being in close contact with each said conductor.

References Cited in the file of this patent UNITED STATES PATENTS 2,043,754 Johnson June 9, 1936 2,138,571 Dehmel Nov. 29, 1938 2,441,804 Farry May 18, 1948 FOREIGN PATENTS 542,360 France May 16, 1922 1,128,165 France Aug. 20, 1956 

